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        <td class="header">&nbsp;&nbsp;<b><span style="font-size: 14pt; line-height: 115%;" lang="EN">IEM
Multi-Polarization Inversion</span></b>
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<p class="MsoNormal" style=""><span style="" lang="EN">There is a strong correlation between soil
dielectric and radar
backscatter. By inverting the Integral Equation Model (IEM), the real
dielectric constant (RDC) can be obtained from the radar backscatter
coefficient. The inversion is accomplished by using a Look Up Table
(LUT). A k-d tree is used to store the LUT for searching.</span></p>
<p class="MsoNormal" style="">To
    address the possibility of multiple roots in the model inversion, an
    iterative approach is adopted. The first pass produces the closest
    match RDC value in each pixel. In the second pass, a representative
    first-pass RDC value (mean is used) is derived from a square
    neighbourhood centred at the pixel (excluding the centre). This
    representative value is compared with the pixel's own first-pass RDC
    value. If it deviates too much from its neighbours, it is labelled as
    an outlier.&nbsp;</p>
<p class="MsoNormal" style="">For each outlier,
    the RDC value with the least deviation among the N closest
    backscattering coefficients from the LUT is used to replace the
    first-pass value. If no such RDC value exists or the deviation is still
    too high, then the RDC value is optionally filtered by replacing it
    with the representative value. If rms is output, it will also be replaced by its representative (mean) value. <span
            style="" lang="EN"></span></p>
<p class="MsoNormal" style=""><b><span style="" lang="EN">Multi-Polarization Approach</span></b></p>
<p class="MsoNormal" style=""><span style="" lang="EN">The Multi-Polarization approach utilizes the HH
and VV backscatter
coefficients in either the AM or PM image (but not both).</span></p>
<p class="MsoNormal" style=""><b><span style="" lang="EN">Calibrated IEM LUT</span></b></p>
<p class="MsoNormal" style=""><span style="" lang="EN">User can browse for a calibrated&nbsp;</span><a
        href="IEM-LUT.html">IEM LUT</a><span style="" lang="EN">. Matlab
(.mat) and CSV (.csv) formats are supported. </span></p>
<p class="MsoNormal" style=""><b><span style="" lang="EN">Parameters Used</span></b><span style="" lang="EN"></span>
</p>
<p class="MsoNormal" style=""><span style="" lang="EN">The source bands used are the HH and VV
backscatter coefficients as well as
the local incidence angles in one image.</span></p>
<p class="MsoNormal" style="font-weight: bold;">UI Parameters</p>
<p class="MsoNormal" style=""><span style="font-weight: bold;">N</span> : &nbsp;This is the number of&nbsp;closest&nbsp;matches
    to request from the kd-tree.</p>
<p class="MsoNormal" style=""><span style="font-weight: bold;">M</span>: &nbsp; This is the length (in pixels) of the
    side of the square neighbour. It must be odd and greater than 1.&nbsp;</p>
<p class="MsoNormal" style=""><span style="font-weight: bold;">RDC deviation threshold</span>:
    &nbsp;The RDC deviation is the absolute difference between the RDC
    value and the mean RDC of the neighbourhood pixels, as a fraction of
    the mean RDC. This is the threshold above which the pixel is labelled
    an outlier.</p>
<p class="MsoNormal"><span style="font-weight: bold;">Filter remaining outliers</span>: Checkbox for optional filter
    using the mean of the neighbouring RDC.<span style="" lang="EN"></span></p>
<p class="MsoNormal" style=""><b><span style="" lang="EN">Outputs</span></b><span style="" lang="EN"></span>
</p>
<p class="MsoNormal" style="">The RDC from the LUT
    is output as a band.<br>
    <br>
    <span style="" lang="EN">User can also optionally
output the RMS roughness height (rms)&nbsp;from the LUT as a band.</span></p>

<p class="MsoNormal" style=""><span style="" lang="EN">If sand and clay percentages are present as source
bands, they will be
copied from the input product to the output product.</span></p>&nbsp; An optional outlier band outputs the outlier
status of the pixel:<br>
<ul>
    <li>0 means the first-pass RDC value has not been replaced</li>
    <li>1 means the first-pass RDC value has been replaced by another &#8216;better&#8217; possible root</li>
    <li>2 means &nbsp;the first-pass RDC value has been replaced by the representative value derived from its
        neighbours
    </li>
</ul>
<p>The
    output of this optional outlier band is controlled by setting a
    preference called "snap.soil_moisture.output_outlier" in the
    snap.properties file in &nbsp;the folder
    "snap-desktop\snap-application\target\snap\etc".</p>
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